Uffe Flarup Laurent Lyaudet On the Expressive Power of Permanents and Perfect Matchings of Matrices of Bounded Pathwidth/Cliquewidth (Extended Abstract). 180-193 2008 CSR http://dx.doi.org/10.1007/978-3-540-79709-8_20 conf/csr/2008 db/conf/csr/csr2008.html#FlarupL08